The present invention relates to a lipopolysaccharide and a process for the preparation thereof. More specifically, the present invention relates to a lipopolysaccharide having physiological activities such as anti-tumor activity, immunizing activity, cell juvenescent activity, phagocyte activating activity and infection preventing activity and a process for preparing efficiently this lipopolysaccharide from actinomycetes and related bacteria.
Bacteria, especially bovine tubercle bacillus, BCG cell body and anaerobic Corynebacterium cell body, have been used as anti-tumor agents or immunizing agents, and it has been shown that these bacteria are effective. However, they have apparently strong side effects.
Attempts have been made to find bacteria having high effectivity without side effects, and trials have been vigorously made to remove components causing side effects from effective cells and isolate and purify effective components.
Researches have been made on the activities of cell body components of bacteria belonging to the genera Mycobacterium, Propionibacterium, Nocardia, etc., and various components having physiological activities have been isolated and purified and trials have been made to prepare substances having higher activities by modifying these components. For example, a cell wall skeleton component (see, for example, Japanese Patent Application laid open to public under No. 28813/1979), muramyl dipeptide (see, for example, Japanese Patent Application laid open to public under No. 156812/1977), a modified product of said dipeptide (see, for example, Japanese Patent Application laid open to public under No. 98922/1978), a glycolipid containing a long-chain fatty acid (see Japanese Patent Application laid open to public under No. 28830/1979) and a hot water extract (see Japanese Patents published under Nos. 6393/1961 and 43842/1973) have been shown. Furthermore, there has recently been disclosed a lipopolysaccharide obtained by purifying a hot water extract of cell body of human tubercle bacillus and a synthetic lipopolysaccharide obtained by coupling this lipopolysaccharide with a fatty acid through an ester linkage (see Japanese Patent Application laid open to public under No. 8320/1981).
We have made researches with a view to developing effective components having immunizing activity, anti-tumor activity and cell juvenescent activity without side effects from bacteria such as Mycobacterium tuberculosis strain Aoyama B (a human tubercle bacillus), Mycobacterium bovis (a bovine tubercle bacillus) and Propionibacterium acnes (a nonpathogenic anaerobic bacillus). As the result, we have found that if a non-ionic surface active agent is used in an extraction treatment of cells of these bacteria, substances causing side effects can be separated very easily without complicated operations such as those adopted in the conventional processes and a lipopolysaccharide having high anti-tumor activity, high immunizing activity and other physiological activities can be obtained efficiently. We have now completed the present invention based on this finding.